Nullify IServerUpdateExecutor

src/Tgstation.Server.Host/Core/IServerUpdateExecutor.cs

@@ -1,8 +1,6 @@
 using System.Threading;
 using System.Threading.Tasks;
 
-#nullable disable
-
 namespace Tgstation.Server.Host.Core
 {
 	/// <summary>

src/Tgstation.Server.Host/Server.cs

@@ -176,6 +176,9 @@ namespace Tgstation.Server.Host
 
 			CheckSanity(true);
 
+			if (updatePath == null)
+				throw new InvalidOperationException("Tried to start update when server was initialized without an updatePath set!");
+
 			var logger = this.logger!;
 			logger.LogTrace("Begin ApplyUpdate...");